Information retrieval systems for financial information, such as stock market type of information and money market information, normally employ a transfer of data in a high-performance, real-time information retrieval network in which update rates, retrieval rates and subscriber and/or user population are generally very high. An example of such a system is REUTERS DEALING SERVICE which is used in the foreign exchange or money market. Such systems, while providing rapid video conversation capability, are not anonymous systems nor do they provide for automated anonymous trading such as is possible in a matching system. Of course, conversational dealing systems have their place in the market and serve particular needs where appropriate. However, anonymous matching systems are also often desired and, by their very nature, do not normally employ a conversation capability since the parties to the transactions are unknown until the transaction has been completed. Examples of satisfactory prior art video conversational systems for use in connection with trading of financial information are disclosed in commonly owned U.S. Pat. Nos. 4,531,184;4,525,779 and 4,404,551, by way of example. Prior art examples of matching systems used in connection with the trading of trading instruments are disclosed in U.S. Pat. No. 4,412,287, which discloses as an automated stock exchange in which a computer matches buy and sell orders for a variety of stocks; U.S. Pat. No. 3,573,747, which discloses an anonymous trading system for selling fungible properties between subscribers to the system; U.S. Pat. No. 3,581,072, which discloses the use of a special purpose digital computer for matching orders and establishing market prices in an auction market for fungible goods; and U.S. Pat. No. 4,674,044, which discloses an automated securities trading system. However, none of these prior art matching systems implements or suggests the use of a broadcast capability for messages from the host computer or central system which is employed to update a trading book of bids and offers locally stored at the keystations to provide restricted subsets of the host book at these keystations. In Addition, no prior art matching systems are known to applicants in which directed messages are employed between the keystations in the system and the central system to update the local entry order data bases and broadcast messages are employed to update the keystation book which is a restricted subset of the host or central system book. Moreover, none of these prior art system employ summary books at the local keystations as subsets of the host or central system book.
In the system of the present invention, as opposed to the prior art known to applicants, the central system maintains a data base consisting of all of the trading instruments available for trade, credit information, and the bids and offers that are present throughout the system, while the client sites or keystations maintain copies of only the best bids and offers and use those to generate a display. Thus, the client sites have some restricted subset of the total depth of the system book located at the central data base. By transmitting only subsets of the total system book from the host, the amount of network overhead that is required is significantly reduced, which reduction is further enhanced by the use of only summary information in the keystation books. Moreover, this enables the central data base maintaining a full set of information for every entry including identification of the parties which identification is not to be provided for the subset books at the keystations in an anonymous trading system. The only time that the keystation is made aware of the parties involved in the transaction is after the transaction has been completed. Thus, in the system of the present invention, the host may enforce a structure on the client site data bases which is the maximum depth of displayable queue or display depth for a particular trading instrument. By a single parameter change at the host or central system, the view of the trading instrument throughout the entire matching system "world" can be effectively changed. For example, if the host system sets the display depth equal to one, then none of the keystations would be able to look further into the book. If desired, this procedure can be dynamically varied from the host so that at given times or given days different aspects of the trading environment can be displayed. Although, dynamic control of the content of a local receiver data base from a transmitted data base in an information retrieval communication network has been previously employed by applicants assignee such as disclosed in U.S. Pat. Nos. 4,745,559 and 4,750,135, these systems are different from the type of system control employed in the system of the present invention in which restricted subsets of the host book are maintained as summary books at the keystation local data bases. Thus, the system of the present invention for providing a distributed matching system overcomes the disadvantages of the prior art.